Systems and methods for a single spiral electrode assembly forming a spherical basket for improved tissue contact and current delivery

ABSTRACT

The disclosed technology includes a medical probe including a tubular shaft having a proximal end and a distal end. The tubular shaft can extend along a longitudinal axis. The medical probe can include an expandable basket assembly proximate the distal end of the tubular shaft. The expandable basket assembly can include a single spine comprising a resilient material extending generally linearly along the longitudinal axis in a collapsed form and forming a spiral member defining a generally spherical outer periphery in an expanded form. One or more electrodes can be coupled to the single spine. Each electrode can include a lumen offset with respect to a centroid of the electrode so that the single spine extends through the lumen of each of the one or more electrodes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119 to prior filed U.S. Provisional Patent Application No. 63/301,096 filed on Jan. 20, 2022, the entire contents of which is hereby incorporated by reference as if set forth in full herein.

FIELD

The present invention relates generally to medical devices, and in particular catheters with electrodes, and further relates to, but not exclusively, catheters suitable for use to induce irreversible electroporation (IRE) of cardiac tissues.

BACKGROUND

Cardiac arrhythmias, such as atrial fibrillation (AF), occur when regions of cardiac tissue abnormally conduct electric signals to adjacent tissue. This disrupts the normal cardiac cycle and causes asynchronous rhythm. Certain procedures exist for treating arrhythmia, including surgically disrupting the origin of the signals causing the arrhythmia and disrupting the conducting pathway for such signals. By selectively ablating cardiac tissue by application of energy via a catheter, it is sometimes possible to cease or modify the propagation of unwanted electrical signals from one portion of the heart to another.

Many current ablation approaches in the art tend to utilize radiofrequency (RF) electrical energy to heat tissue. RF ablation can have certain rare drawbacks due to operator's skill, such as heightened risk of thermal cell injury which can lead to tissue charring, burning, steam pop, phrenic nerve palsy, pulmonary vein stenosis, and esophageal fistula. Cryoablation is an alternative approach to RF ablation that generally reduces thermal risks associated with RF ablation but may present tissue damage due to the very low temperature nature of such devices. Maneuvering cryoablation devices and selectively applying cryoablation, however, is generally more challenging compared to RF ablation; therefore cryoablation is not viable in certain anatomical geometries which may be reached by electrical ablation devices.

Some ablation approaches use irreversible electroporation (IRE) to ablate cardiac tissue using nonthermal ablation methods. IRE delivers short pulses of high voltage to tissues and generates an unrecoverable permeabilization of cell membranes. Delivery of IRE energy to tissues using multi-electrode catheters was previously proposed in the patent literature. Examples of systems and devices configured for IRE ablation are disclosed in U.S. Patent Pub. No. 2021/0169550A1, 2021/0169567A1, 2021/0169568A1, 2021/0161592A1, 2021/0196372A1, 2021/0177503A1, and 2021/0186604A1, each of which are incorporated by reference in their entirety into this application as if set forth in full and attached in the appendix to priority application U.S. 63/301,096.

Regions of cardiac tissue can be mapped by a catheter to identify the abnormal electrical signals. The same or different catheter can be used to perform ablation. Some example catheters include a number of spines with electrodes positioned thereon. The electrodes are generally attached to the spines and secured in place by soldering, welding, or using an adhesive. Furthermore, multiple linear spines are generally assembled together by attaching both ends of the linear spines to a tubular shaft (e.g., a pusher tube) to form a spherical basket. Due to the small size of the spines and the electrodes, however, adhering the electrodes to the spines and then forming a spherical basket from the multiple linear spines can be a difficult task, increasing the manufacturing time and cost and the chances that the electrode fails due to an improper bond or misalignment. What is needed, therefore, are devices and methods of forming an improved basket assembly that can position the electrodes in the proper location when in an expanded state while also reducing the overall manufacturing complexity of the basket assembly.

SUMMARY

Various embodiments of a medical probe, including certain methods related thereto are provided. In one exemplary embodiment (out of many), a medical probe including a tubular shaft having a proximal end and a distal end. The tubular shaft can extend along a longitudinal axis. The medical probe can include an expandable basket assembly proximate the distal end of the tubular shaft. The expandable basket assembly can include a single spine comprising a resilient material extending generally linearly along the longitudinal axis in a collapsed form and forming a spiral member defining a generally spherical outer periphery in an expanded form. One or more electrodes can be coupled to the single spine. Each electrode can include a lumen offset with respect to a centroid of the electrode so that the single spine extends through the lumen of each of the one or more electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic pictorial illustration of a medical system comprising a medical probe whose distal end comprises a basket assembly with electrodes, in accordance with an embodiment of the present invention;

FIG. 2 is a schematic pictorial illustration showing a perspective view of a medical probe in an expanded form, in accordance with an embodiment of the present invention;

FIG. 3 is a schematic pictorial illustration showing an exploded side view of a medical probe in an expanded form, in accordance with the disclosed technology.

FIG. 4 is a schematic pictorial illustration showing a side view of a medical probe in a collapsed form, in accordance with the disclosed technology;

FIG. 5 is a schematic pictorial illustration of a method of forming a spine from a planar sheet of resilient material, in accordance with the disclosed technology;

FIG. 6 is a schematic pictorial illustration of a method of forming a spine from a cylindrical hollow tube of resilient material, in accordance with the disclosed technology;

FIGS. 7A-7J are schematic pictorial illustrations showing a perspective view of various example electrodes, in accordance with the disclosed technology;

FIGS. 8A and 8B are schematic pictorial illustrations showing various insulative jackets of a given medical device, in accordance with embodiments of the present invention;

FIGS. 9A and 9B are schematic pictorial illustrations showing cross-sectional views of a given wire of a medical probe, in accordance with an embodiment of the present invention;

FIG. 10 is a flowchart illustrating a method of assembling a basket assembly, in accordance with an embodiment of the present invention;

FIG. 11 is a flowchart illustrating another method of assembling a basket assembly, in accordance with an embodiment of the present invention;

FIG. 12 is a flowchart illustrating another method of assembling a basket assembly, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.

As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±20% of the recited value, e.g. “about 90%” may refer to the range of values from 71% to 110%.

As used herein, the term “proximal” indicates a location closer to the operator or physician whereas “distal” indicates a location further away to the operator or physician.

As discussed herein, vasculature of a “patient,” “host,” “user,” and “subject” can be vasculature of a human or any animal. It should be appreciated that an animal can be a variety of any applicable type, including, but not limited thereto, mammal, veterinarian animal, livestock animal or pet type animal, etc. As an example, the animal can be a laboratory animal specifically selected to have certain characteristics similar to a human (e.g., rat, dog, pig, monkey, or the like). It should be appreciated that the subject can be any applicable human patient, for example.

As discussed herein, “operator” can include a doctor, surgeon, technician, scientist, or any other individual or delivery instrumentation associated with delivery of a multi-electrode catheter for the treatment of drug refractory atrial fibrillation to a subject.

As discussed herein, the term “ablate” or “ablation”, as it relates to the devices and corresponding systems of this disclosure, refers to components and structural features configured to reduce or prevent the generation of erratic cardiac signals in the cells by utilizing non-thermal energy, such as irreversible electroporation (IRE), referred throughout this disclosure interchangeably as pulsed electric field (PEF) and pulsed field ablation (PFA). Ablating or ablation as it relates to the devices and corresponding systems of this disclosure is used throughout this disclosure in reference to non-thermal ablation of cardiac tissue for certain conditions including, but not limited to, arrhythmias, atrial flutter ablation, pulmonary vein isolation, supraventricular tachycardia ablation, and ventricular tachycardia ablation. The term “ablate” or “ablation” also includes known methods, devices, and systems to achieve various forms of bodily tissue ablation as understood by a person skilled in the relevant art.

As discussed herein, the terms “bipolar” and “unipolar” when used to refer to ablation schemes describe ablation schemes which differ with respect to electrical current path and electric field distribution. “Bipolar” refers to ablation scheme utilizing a current path between two electrodes that are both positioned at a treatment site; current density and electric flux density is typically approximately equal at each of the two electrodes. “Unipolar” refers to ablation scheme utilizing a current path between two electrodes where one electrode having a high current density and high electric flux density is positioned at a treatment site, and a second electrode having comparatively lower current density and lower electric flux density is positioned remotely from the treatment site.

As discussed herein, the terms “biphasic pulse” and “monophasic pulse” refer to respective electrical signals. “Biphasic pulse” refers to an electrical signal having a positive-voltage phase pulse (referred to herein as “positive phase”) and a negative-voltage phase pulse (referred to herein as “negative phase”). “Monophasic pulse” refers to an electrical signal having only a positive or only a negative phase. Preferably, a system providing the biphasic pulse is configured to prevent application of a direct current voltage (DC) to a patient. For instance, the average voltage of the biphasic pulse can be zero volts with respect to ground or other common reference voltage. Additionally, or alternatively, the system can include a capacitor or other protective component. Where voltage amplitude of the biphasic and/or monophasic pulse is described herein, it is understood that the expressed voltage amplitude is an absolute value of the approximate peak amplitude of each of the positive-voltage phase and/or the negative-voltage phase. Each phase of the biphasic and monophasic pulse preferably has a square shape having an essentially constant voltage amplitude during a majority of the phase duration. Phases of the biphasic pulse are separated in time by an interphase delay. The interphase delay duration is preferably less than or approximately equal to the duration of a phase of the biphasic pulse. The interphase delay duration is more preferably about 25% of the duration of the phase of the biphasic pulse.

As discussed herein, the terms “tubular” and “tube” are to be construed broadly and are not limited to a structure that is a right cylinder or strictly circumferential in cross-section or of a uniform cross-section throughout its length. For example, the tubular structures are generally illustrated as a substantially right cylindrical structure. However, the tubular structures may have a tapered or curved outer surface without departing from the scope of the present disclosure.

The term “temperature rating”, as used herein, is defined as the maximum continuous temperature that a component can withstand during its lifetime without causing thermal damage, such as melting or thermal degradation (e.g., charring and crumbling) of the component.

The present disclosure is related to systems, methods or uses and devices which utilize end effectors having electrodes affixed to spines. Example systems, methods, and devices of the present disclosure may be particularly suited for IRE ablation of cardiac tissue to treat cardiac arrhythmias. Ablative energies are typically provided to cardiac tissue by a tip portion of a catheter which can deliver ablative energy alongside the tissue to be ablated. Some example catheters include three-dimensional structures at the tip portion and are configured to administer ablative energy from various electrodes positioned on the three-dimensional structures. Ablative procedures incorporating such example catheters can be visualized using fluoroscopy.

Ablation of cardiac tissue using application of a thermal technique, such as radio frequency (RF) energy and cryoablation, to correct a malfunctioning heart is a well-known procedure. Typically, to successfully ablate using a thermal technique, cardiac electropotentials need to be measured at various locations of the myocardium. In addition, temperature measurements during ablation provide data enabling the efficacy of the ablation. Typically, for an ablation procedure using a thermal technique, the electropotentials and the temperatures are measured before, during, and after the actual ablation.

RF approaches can have risks that can lead to tissue charring, burning, steam pop, phrenic nerve palsy, pulmonary vein stenosis, and esophageal fistula. Cryoablation is an alternative approach to RF ablation that can reduce some thermal risks associated with RF ablation. However maneuvering cryoablation devices and selectively applying cryoablation is generally more challenging compared to RF ablation; therefore cryoablation is not viable in certain anatomical geometries which may be reached by electrical ablation devices.

IRE as discussed in this disclosure is a non-thermal cell death technology that can be used for ablation of atrial arrhythmias. To ablate using IRE/PEF, biphasic voltage pulses are applied to disrupt cellular structures of myocardium. The biphasic pulses are non-sinusoidal and can be tuned to target cells based on electrophysiology of the cells. In contrast, to ablate using RF, a sinusoidal voltage waveform is applied to produce heat at the treatment area, indiscriminately heating all cells in the treatment area. IRE therefore has the capability to spare adjacent heat sensitive structures or tissues which would be of benefit in the reduction of possible complications known with ablation or isolation modalities. Additionally, or alternatively, monophasic pulses can be utilized.

Electroporation can be induced by applying a pulsed electric field across biological cells to cause reversible (temporary) or irreversible (permanent) creation of pores in the cell membrane. The cells have a transmembrane electrostatic potential that is increased above a resting potential upon application of the pulsed electric field. While the transmembrane electrostatic potential remains below a threshold potential, the electroporation is reversible, meaning the pores can close when the applied pulse electric field is removed, and the cells can self-repair and survive. If the transmembrane electrostatic potential increases beyond the threshold potential, the electroporation is irreversible, and the cells become permanently permeable. As a result, the cells die due to a loss of homeostasis and typically die by programmed cell death or apoptosis, which is believed to leave less scar tissue as compared to other ablation modalities. Generally, cells of differing types have differing threshold potential. For instance, heart cells have a threshold potential of approximately 500 V/cm, whereas for bone it is 3000 V/cm. These differences in threshold potential allow IRE to selectively target tissue based on threshold potential.

The solution of this disclosure includes systems and methods for applying electrical signals from catheter electrodes positioned in the vicinity of myocardial tissue, preferably by applying a pulsed electric field effective to induce electroporation in the myocardial tissue. The systems and methods can be effective to ablate targeted tissue by inducing irreversible electroporation. In some examples, the systems and methods can be effective to induce reversible electroporation as part of a diagnostic procedure. Reversible electroporation occurs when the electricity applied with the electrodes is below the electric field threshold of the target tissue allowing cells to repair. Reversible electroporation does not kill the cells but allows a physician to see the effect of reversible electroporation on electrical activation signals in the vicinity of the target location. Example systems and methods for reversible electroporation is disclosed in U.S. Patent Publication 2021/0162210, the entirety of which is incorporated by reference in its entirety into this application as if set forth in full and attached in the appendix to priority application U.S. 63/301,096.

The pulsed electric field, and its effectiveness to induce reversible and/or irreversible electroporation, can be affected by physical parameters of the system and biphasic pulse parameters of the electrical signal. Physical parameters can include electrode contact area, electrode spacing, electrode geometry, etc. examples presented herein generally include physical parameters adapted to effectively induce reversible and/or irreversible electroporation. Biphasic pulse parameters of the electrical signal can include voltage amplitude, pulse duration, pulse interphase delay, inter-pulse delay, total application time, delivered energy, etc. In some examples, parameters of the electrical signal can be adjusted to induce both reversible and irreversible electroporation given the same physical parameters. Examples of various systems and methods of ablation including IRE are presented in U.S. Patent Publications 2021/0169550A1, 2021/0169567A1, 2021/0169568A1, 2021/0161592A1, 2021/0196372A1, 2021/0177503A1, and 2021/0186604A1, the entireties of each of which are incorporated by reference in their entirety into this application as if set forth in full and attached in the appendix to priority application U.S. 63/301,096.

To deliver pulsed field ablation (PFA) in an IRE (irreversible electroporation) procedure, electrodes should contact the tissue being ablated with a sufficiently large surface area. As described hereinbelow, the medical probe includes a tubular shaft having proximal and distal ends, and a basket assembly at the distal end of the tubular shaft. The basket assembly includes a spine and a plurality of electrode assemblies. The spine can form a spiral member defining a generally spherical outer periphery when in an expanded form.

FIG. 1 is a schematic, pictorial illustration of a medical system 20 including a medical probe 22 and a control console 24, in accordance with an embodiment of the present invention. Medical system 20 may be based, for example, on the CARTO® system, produced by Biosense Webster Inc. of 31 Technology Drive, Suite 200, Irvine, Calif. 92618 USA. In embodiments described hereinbelow, medical probe 22 can be used for diagnostic or therapeutic treatment, such as for performing ablation procedures in a heart 26 of a patient 28. Alternatively, medical probe 22 may be used, mutatis mutandis, for other therapeutic and/or diagnostic purposes in the heart or in other body organs.

Medical probe 22 includes a flexible insertion tube 30 and a handle 32 coupled to a proximal end of the insertion tube. During a medical procedure, a medical professional 34 can insert probe 22 through the vascular system of patient 28 so that a distal end 36 of the medical probe enters a body cavity such as a chamber of heart 26. Upon distal end 36 entering the chamber of heart 26, medical professional 34 can deploy a basket assembly 38 approximate a distal end 36 of the medical probe 22. Basket assembly 38 can include a plurality of electrodes 40 affixed to a plurality of spines, as described in the description referencing FIGS. 2A and 2B hereinbelow. To start performing a medical procedure such as irreversible electroporation (IRE) ablation, medical professional 34 can manipulate handle 32 to position distal end 36 so that electrodes 40 engage cardiac tissue at a desired location or locations. Upon positioning the distal end 36 so that electrodes 40 engages cardiac tissue, the medical professional 34 can activate the medical probe 22 such that electrical pulses are delivered by the electrodes 40 to perform the IRE ablation.

The medical probe 22 can include a guide sheath and a therapeutic catheter, wherein the guide sheath includes the flexible insertion tube 30 and the handle 32 and the therapeutic catheter includes the basket assembly 38, electrodes 40, and a tubular shaft 84 (see FIGS. 2 through 4 ). The therapeutic catheter is translated through the guide sheath so that the basket assembly 38 is positioned in the heart 26. The distal end 36 of the medical probe 22 corresponds to a distal end of the guide sheath when the basket assembly 38 is contained within the flexible insertion tube 30, and the distal end 36 of the medical probe 22 corresponds to a distal end of the basket assembly 38 when the basket assembly 38 is extended from the distal end of the guide sheath. The medical probe 22 can be alternatively configured to include a second handle on the therapeutic catheter and other features as understood by a person skilled in the pertinent art.

In the configuration shown in FIG. 1 , control console 24 is connected, by a cable 42, to body surface electrodes, which typically include adhesive skin patches 44 that are affixed to patient 28. Control console 24 includes a processor 46 that, in conjunction with a tracking module 48, determines location coordinates of distal end 36 inside heart 26. Location coordinates can be determined based on electromagnetic position sensor output signals provided from the distal portion of the catheter when in the presence of a generated magnetic field. Location coordinates can additionally, or alternatively be based on impedances and/or currents measured between adhesive skin patches 44 and electrodes 40 that are affixed to basket assembly 38. In addition to being used as location sensors during a medical procedure, electrodes 40 may perform other tasks such as ablating tissue in the heart.

As described hereinabove, in conjunction with tracking module 48, processor 46 may determine location coordinates of distal end 36 inside heart 26 based on impedances and/or currents measured between adhesive skin patches 44 and electrodes 40. Such a determination is typically after a calibration process relating the impedances or currents to known locations of the distal end has been performed. While embodiments presented herein describe electrodes 40 that are preferably configured to deliver IRE ablation energy to tissue in heart 26, configuring electrodes 40 to deliver any other type of ablation energy to tissue in any body cavity is considered to be within the spirit and scope of the present invention. Furthermore, although described in the context of being electrodes 40 that are configured to deliver IRE ablation energy to tissue in the heart 26, one skilled in the art will appreciate that the disclosed technology can be applicable to electrodes used for mapping and/or determining various characteristics of an organ or other part of the patient's 28 body.

Processor 46 may include real-time noise reduction circuitry 50 typically configured as a field programmable gate array (FPGA), followed by an analog-to-digital (A/D) signal conversion integrated circuit 52. The processor can be programmed to perform one or more algorithms and uses circuitry 50 and circuit 52 as well as features of modules to enable the medical professional 34 to perform the IRE ablation procedure.

Control console 24 also includes an input/output (I/O) communications interface 54 that enables control console 24 to transfer signals from, and/or transfer signals to electrodes 40 and adhesive skin patches 44. In the configuration shown in FIG. 1 , control console 24 additionally includes an IRE ablation module 56 and a switching module 58.

IRE ablation module 56 is configured to generate IRE pulses having peak power in the range of tens of kilowatts. In some examples, the electrodes 40 are configured to deliver electrical pulses having a peak voltage of at least 900 volts (V). The medical system 20 performs IRE ablation by delivering IRE pulses to electrodes 40. Preferably, the medical system 20 delivers biphasic pulses between electrodes 40 on the spine. Additionally, or alternatively, the medical system 20 delivers monophasic pulses between at least one of the electrodes 40 and a skin patch.

The system 20 may supply irrigation fluid (e.g., a saline solution) to distal end 36 and to the electrodes 40 via a channel (not shown) in the tubular shaft 84 (see FIGS. 2 through 4 ). Irrigation is sometimes utilized to reduce clot formation, stagnant blood flow or even reduce heat generated by ablation via the electrodes. Additionally, or alternatively, irrigation fluid can be supplied through the flexible insertion tube 30. Control console 24 includes an irrigation module 60 to monitor and control irrigation parameters, such as the pressure and the temperature of the irrigation fluid. It is noted that while the preference for the exemplary embodiments of the medical probe is for IRE or PFA, it is within the scope of the present invention to also use the medical probe separately only for RF ablation (unipolar mode with an external grounding electrode or bipolar mode) or in combination with IRE and RF ablations sequentially (certain electrodes in IRE mode and other electrodes in RF mode) or simultaneously (groups of electrodes in IRE mode and other electrodes in RF mode).

Based on signals received from electrodes 40 and/or adhesive skin patches 44, processor 46 can generate an electroanatomical map 62 that shows the location of distal end 36 in the patient's body. During the procedure, processor 46 can present map 62 to medical professional 34 on a display 64, and store data representing the electroanatomical map in a memory 66. Memory 66 may include any suitable volatile and/or non-volatile memory, such as random-access memory or a hard disk drive.

In some embodiments, medical professional 34 can manipulate map 62 using one or more input devices 68. In alternative embodiments, display 64 may include a touchscreen that can be configured to accept inputs from medical professional 34, in addition to presenting map 62.

FIG. 2 is a schematic pictorial illustration showing a perspective view of a medical probe 22 with a basket assembly 38 in an expanded form when unconstrained, such as by being advanced out of an insertion tube lumen 80 at a distal end 36 of an insertion tube 30. The medical probe 22 illustrated in FIG. 2 lacks the guide sheath illustrated in FIG. 1 . FIG. 3 is an exploded view of the medical probe 22 and basket assembly 38 once again showing the basket assembly 38 in an expanded form while FIG. 4 shows the basket assembly 38 in a collapsed form within the insertion tube 30 of the guide sheath. In the expanded form (FIGS. 2 and 3 ), the spine 214 forms a spherical spiral shape and in the collapsed form (FIG. 4 ), the spine 214 is arranged generally along a longitudinal axis 86 of insertion tube 30.

As shown in FIG. 2 , basket assembly 38 includes a single spine 214 that is attached to an end of a tubular shaft 84. During a medical procedure, medical professional 34 can deploy basket assembly 38 by extending tubular shaft 84 from insertion tube 30 (shown in FIG. 4 ) causing the basket assembly 38 to exit the insertion tube and transition to the expanded form. Spine 214 may have an elliptical (e.g., circular) or a rectangular (that may appear to be flat) cross-section, and include a flexible, resilient material (e.g., a shape-memory alloy such as nickel-titanium (also known as Nitinol), cobalt chromium, or any other suitable material).

In embodiments described herein, electrodes 40 can be configured to deliver ablation energy (RF and/or IRE) to tissue in heart 26. Additionally, or alternatively, the electrodes can also be used to determine the location of basket assembly 38 and/or to measure a physiological property such as local surface electrical potentials at respective locations on tissue in heart 26. As described further herein, the electrodes 40 can be biased such that a greater portion of the electrode 40 faces outwardly from the basket assembly 39 such that the electrodes 40 deliver a greater amount of electrical energy outwardly away from the basket assembly 38 (i.e., toward the heart 26 tissue) than inwardly toward the basket assembly 38.

Examples of materials ideally suited for forming electrodes 40 include gold, platinum, and palladium (and their respective alloys). These materials also have high thermal conductivity which allows the minimal heat generated on the tissue (i.e., by the ablation energy delivered to the tissue) to be conducted through the electrodes to the back side of the electrodes (i.e., the portions of the electrodes on the inner sides of the spines), and then to the blood pool in heart 26.

As illustrated in FIG. 2 , the spine 214 can form a generally spherical spiral shape when in an expanded form. For example, the spine 214 can have a first end that is disposed proximate the distal end of the tubular shaft 84 and a second end that is positioned proximate a distal end 36 of the medical probe 22 (i.e., the second end of the spine 214 can be the distal end 36 of the medical probe 22 when the basket assembly 38 is in the expanded form). When in the expanded form, the spine 214 can spiral outwardly from the first end to a first location along the spine that is between the first end and the second end. The spine 214 can spiral inwardly from the first location to the second end to complete the spherical spiral shape.

The electrodes 40 can be spaced along the spine 214 such that the electrodes 40 are configured to face outwardly and are positioned to contact, or nearly contact, the cardiac tissue when the basket assembly 38 is in the expanded form. In this way, the basket assembly 38 can be configured to position the electrodes 40 to facilitate the IRE ablation procedure. For example, the electrodes 40 can be spaced along the spine 214 such that an electrode disposed along a first turn of the spiral can be offset in relation to a second electrode 40 that is disposed along a second turn of the spiral. In other words, the electrodes 40 can be offset from an adjacent electrode 40 to ensure the basket assembly 38 is able to sufficiently deliver electrical pulses to the cardiac tissue.

FIG. 3 is a schematic pictorial illustration showing an exploded side view of a medical probe 22 in an expanded form, in accordance with the disclosed technology. As illustrated in FIG. 3 , the spine 214 can be a spiral shape such that a periphery of the basket assembly 38 forms a generally spherical shape when in an expanded form. The spine 214 can be configured to form the generally spherical shape with a predetermined diameter D when in the expanded form. The diameter D can be sized to ensure the basket assembly 38 can fit within a chamber of the heart and so that the electrodes 40 are sufficiently spaced to perform the IRE ablation procedure. The spine 214 can also be configured such that the periphery of the basket assembly 38 forms an oblate-spheroid shape when in an expanded form such that a distance between a proximal end and a distal end of the basket 38 is closer together when compared to the spherically-shaped basket. The oblate-spheroid shape can have the same diameter D as that of the spherical shape and be sized to ensure the basket assembly 38 can fit within a chamber of the heart and so that the electrodes 40 are sufficiently spaced to perform the IRE ablation procedure.

The medical probe 22 can include a spine retention hub 90 disposed proximate the distal end 85 of the tubular shaft 84. The spine retention hub 90 can be inserted into the tubular shaft 84 and attached to the tubular shaft 84. The spine retention hub 90 can include a cylindrical member comprising a relief land 97 disposed on the outer surface of the cylindrical member to allow the spine 214 to be fitted into the relief land 97 and retained therein. For example, the spine retention hub 90 can include a relief land 97 that is sized to receive an attachment end 216 of the spine 214. The attachment end 216 can be a generally linear end of the spine 214. The attachment end 216 can be configured to extend outwardly from the spine retention hub 90 such that the basket assembly 38 is positioned outwardly from the spine retention hub 90 and, consequently, outwardly from the tubular shaft 84. In this way, the spine 214 can be configured to position the basket assembly 38 distally from the distal end of the tubular shaft 84 and distal from the distal end of the insertion tube 30 when the basket assembly is deployed. The spine retention hub 90 can further include at least one electrode 99 disposed at a distal portion of the spine retention hub 90. Electrode 99 disposed at a distal end of retention hub 90 can be used in combination with electrodes 40 on the spines 214, or alternatively, can be used independently from electrodes 40 for reference mapping or ablation.

As described supra, control console 24 includes irrigation module 60 that delivers irrigation fluid to distal end 36. Spine retention hub 90 can include one or more irrigation openings 98, wherein each given irrigation opening 98 can be angled to spray or otherwise disperse of the irrigation fluid to either a given electrode 40 or to tissue in heart 26. Since electrodes 40 do not include irrigation openings that deliver irrigation fluid, the configuration described herein enables heat to be transferred from the tissue (i.e., during an ablation procedure) to the portion of the electrodes on the inner side of the spine 214, and the electrodes 40 can be cooled by aiming the irrigation fluid, via irrigation openings 98, at the portion of the electrodes 40 on the inner side of the spine 214.

FIG. 4 is a schematic pictorial illustration showing a side view of a medical probe 22 in a collapsed form, in accordance with the disclosed technology. As illustrated in FIG. 4 , the basket assembly 38 can be pulled into the flexible insertion tube 30 such that the spine 214 is disposed generally linearly along a longitudinal axis 86 of the medical probe 22 when in the collapsed form. In other words, when the tubular shaft 84 is pulled into the flexible insertion tube 30, the basket assembly 38 can be pulled along into the flexible insertion tube 30. Because the basket assembly 38 comprises a spine 214 being made from a flexible resilient material, the basket assembly 38 can be elongated such that the spine 214 (and necessarily basket assembly 38) is disposed generally linearly along the longitudinal axis 86 of the medical probe 22. As will be appreciated, however, because the spine 214 comprises a flexible resilient material, the spine 214 may not form a completely straight configuration but may include various bends or curves when pulled into the flexible insertion tube 30.

FIG. 5 is a schematic pictorial illustration of a method of forming a spine 214 from a planar sheet of resilient material 502, in accordance with the disclosed technology. The spine 214 can be formed by cutting a first spiral 214A and a second spiral 214B into the planar sheet of resilient material 502 (e.g., a shape-memory alloy such as nickel-titanium (also known as Nitinol), cobalt chromium, or any other suitable material). The first spiral 214A and the second spiral 214B can be attached to each other with a linear portion 214C. The first spiral 214A and the second spiral 214B can each have a diameter D that are equal in size. The linear portion 214C can have a length L that is the same size as the diameter D or a different size than the diameter D.

After cutting the first spiral 214A, the second spiral 214B, and the linear portion 214C from the planar sheet of resilient material 502, the spine 214 can be formed by forming the first spiral 214A, the second spiral 214B, and the linear portion 214C into a spherical spiral shape. For example, the first spiral 214A can be expanded in a first direction to form a three-dimensional spiral, the second spiral 214B can be expanded in a second direction to form a second three-dimensional spiral, and the linear portion 214C can be coiled or rounded between the first and second spirals 214A, 214B to complete the spherical spiral. The spine 214 can be bent to retain the spherical spiral shape. Alternatively, or in addition, the spine 214 can be heat treated to retain the spherical spiral shape. As well, the spine assembly 210A or 210B can be formed by laser cutting a cylindrical hollow stock material whereby the laser is mounted for rotation about the longitudinal axis (and translation thereto) of the cylindrical stock while cutting through the cylindrical stock. As will be appreciated, the methods described are offered merely for illustrative purposes and should not be construed as limiting.

FIG. 6 is a schematic pictorial illustration of a method of forming at least a portion of a spine 214 from a cylindrical hollow tube of resilient material 602, in accordance with the disclosed technology. As illustrated in FIG. 6 , the spine 214 can be formed from a cylindrical hollow tube of resilient material 602 (e.g., a shape-memory alloy such as nickel-titanium (also known as Nitinol), cobalt chromium, or any other suitable material) by cutting the cylindrical hollow tube of resilient material 602 into spiral sections. For example, by starting at one end of the cylindrical hollow tube of resilient material 602 and cutting the cylindrical hollow tube of resilient material 602 at an angle, a spiral section of the cylindrical hollow tube of resilient material 602 can be formed. The spine 214 can be cut, for example, by spinning the cylindrical hollow tube of resilient material 602 and moving a knife, laser, or other cutting device longitudinally along the length of the cylindrical hollow tube of resilient material 602. Alternatively, the cylindrical hollow tube may be kept stationary while the cutting devices is rotated about the cylindrical hollow tube.

After cutting the spine 214 from the cylindrical hollow tube of resilient material 602, the spine 214 can be formed into a spherical spiral by bending the spine 214 into the spherical spiral shape. The spine 214 can retain the spherical spiral shape simply by being bent into the spherical spiral shape. Alternatively, or in addition, the spine 214 can be heat treated to retain the spherical spiral shape. As will be appreciated, the method just described is offered merely for illustrative purposes and should not be construed as limiting.

Alternatively, or in addition, the spine 214 can be formed by coiling round wire, flat wire, coined flat wire, or other similar types of wire or material to form the spherical spiral. For example, the spine 214 can be formed by bending a round wire (or other selected wire type) until the desired spherical spiral shape is achieved.

Referring back to FIG. 2 through FIG. 4 , one or more electrodes 40 can be attached to spines 214 to form the basket assembly 38. In some examples, each electrode 40 can include electrically conductive material (e.g., gold, platinum and palladium (and their respective alloys)). Turning to FIGS. 7A through 7J, electrode 40 can have a variety of cross-sectional shapes, curvatures, lengths, lumen number and lumen shape as provided as examples in electrodes 740A-740E. The electrodes 740A-740E are offered to illustrate various configurations of electrodes 40 that can be used with the medical device 22 but should not be construed as limiting. One skilled in the art will appreciate that various other configurations of electrodes 40 can be used with the disclosed technology without departing from the scope of this disclosure.

Each electrode 740A-740E can have an outer surface 774 facing outwardly from electrode 740 and an inner surface 776 facing inwardly toward electrode 740 where at least one lumen 770 is formed through electrode 740. The lumen 770 can be sized and configured to receive a spine 214 such that spine 214 can pass through electrode 740. Lumen 770 can be a symmetric opening through electrode 740A-740E and can be disposed offset with respect to a longitudinal axis L-L of the respective electrode. In other examples, lumen 770 can pass through electrode 740 in a generally transverse direction with respect to the longitudinal axis L-L of the respective electrode. Furthermore, lumen 770 can be positioned in electrode 740 nearer a bottom surface, nearer a top surface, or nearer a middle of electrode 740 depending on the particular configuration. In FIGS. 7A, 7C, and 7E through 7J, the top surface is oriented toward the top of the drawing, the bottom surface is oriented toward the bottom of the drawing, and the middle is between the top surface and the bottom surface. In other words, each electrode 740A-740E can include a lumen 770 that is offset with respect to a centroid of the electrode 740A-740E.

In addition, as shown in FIGS. 7A through 7F, electrodes 740A-740C can have a wire relief 772 forming a recess or depression in electrode 740 adjacent lumen 770 for one or more wires to pass through lumen 770 along with a respective spine 214. Relief 772 can be sized to provide room for a wire of electrode 740 to pass through electrode 740 such that electrode 740 can be in electrical communication with the control console 24.

Alternatively, or in addition thereto, wires can pass through a wire lumen 773 as shown in example electrodes 740D and 740E in FIGS. 7G through 7J. Although not depicted, electrodes 40 may include both a wire relief 772 adjacent lumen 770 and wire lumen 773. Such electrode may permit additional wires to pass through the electrode body.

As shown in FIGS. 7A-7J, the electrodes 740A-740E can include various shapes depending on the application. For example, as illustrated in FIGS. 7A and 7B, the electrode 740A can comprise a substantially rectangular cuboid shape with rounded edges. In other examples, the electrode 740B can comprise a substantially ovoid shape (as illustrated in FIGS. 7C and 7D), the electrode 740C, 740D can have a contoured shape having a convex side and a concave side (as illustrated in FIGS. 7E through 7H), or the electrode 740E can have a contoured shape having substantially more material proximate an upper side than a lower side of the electrode 740E (as illustrated in FIGS. 7I and 7J). As will be appreciated by one of skill in the art, the various example electrodes 740A-740E shown in FIGS. 7A-7J, and described herein, are offered for illustrative purposes and should not be construed as limiting.

FIGS. 8A and 8B are schematic pictorial illustrations showing various insulative jackets 880A, 880B of a given medical device 22, in accordance with embodiments of the present invention. FIG. 8A is a front view while FIG. 8B is a perspective view of insulative jackets 880A, 880B. Insulative jackets 880A, 880B can be made from a biocompatible, electrically insulative material such as polyamide-polyether (Pebax) copolymers, polyethylene terephthalate (PET), urethanes, polyimide, parylene, silicone, etc. In some examples, insulative material can include biocompatible polymers including, without limitation, polyetheretherketone (PEEK), polyglycolic acid (PGA), poly(lactic-co-glycolic acid) copolymer (PLGA), polycaprolactive (PCL), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly-L-lactide, polydioxanone, polycarbonates, and polyanhydrides with the ratio of certain polymers being selected to control the degree of inflammatory response. Insulative jackets 880A, 880B may also include one or more additives or fillers, such as, for example, polytetrafluoroethylene (PTFE), boron nitride, silicon nitride, silicon carbide, aluminum oxide, aluminum nitride, zinc oxide, and the like. Insulative jacket 880A, 880B can help to insulate a spine 214 and/or wires passing through insulative jacket 880A, 880B from electrode 40 to prevent arcing from electrode 40 to the spine 214 and/or mechanical abrasion of wires passing through insulative jacket 880A, 880B.

As illustrated in FIGS. 8A and 8B, insulative jackets 880A, 880B, can include a cross-sectional shape that is substantially trapezoidal. The insulative jacket may consist of a single lumen or multi-lumen configuration. Multi-lumen jackets may be configured such that the alloy frame and wires share a single lumen while the second lumen may be used for irrigation. The alloy frame and wires may occupy separate lumens, also, as described. For these designs, the insulative jackets may be continuous (individual sleeves extending from proximal to distal end of each alloy frame strut), segmented (bridging between electrode gaps), or a combination of both. Furthermore, insulative jacket 880A, 880B can include a first lumen 882A, 882B and a second lumen 884A, 884B. First lumen 882A, 882B can be configured to receive spine 214 while second lumen 884A, 884B can be configured to receive a wire, or vice-versa. In other examples, first lumen 882A, 882B and second lumen 884A, 884B can each be configured to receive one or more wires that can be connected to one or more electrodes 40. Furthermore, as illustrated in FIG. 8B, insulative jacket 880A, 880B can include an aperture 886A, 886B through which a wire can be electrically connected to electrode 40. Although illustrated in FIG. 8B as being proximate a bottom of insulative jacket 880A, 880B, aperture 886A, 886B can be positioned proximate a top or side of insulative jacket 880A, 880B. Furthermore, insulative jacket 880A, 880B can include multiple apertures 886A, 886B with each aperture being disposed on the same side of insulative jacket (i.e., top, bottom, left, right) or on different sides of the insulative jacket depending on the application.

FIGS. 9A and 9B are schematic pictorial illustrations showing cross-sectional views of a given wire 900, 950 that can be connected to a given electrode 40, in accordance with an embodiment of the present invention. FIG. 9A illustrates a solid core wire 900. FIG. 9B illustrates a stranded wire 950. Each wire 900, 950 can extend through at least a portion of the tubular shaft 84. Solid core wire 900 can include an electrically conductive core material 902 and an electrically conductive cover material 904 circumscribing electrically conductive core material 902. Likewise, stranded wire 950 can include strands each including an electrically conductive core material 952 and an electrically conductive cover material 954 circumscribing the electrically conductive core material 952. Each wire 900, 950 can include an insulative jacket 906 circumscribing the conductors. The wires 900, 950 can be configured to withstand a voltage difference of adjacent wires sufficient to deliver IRE pulses. Preferably, the wires 900, 950 can withstand at least 900V to 2000V, and more preferably at least 1,800V to 4000V between adjacent wires. To reduce likelihood of dielectric breakdown between conductors of adjacent wires, electrically conductive cover material 904, 954 can have a lower electrical conductivity compared to core material 902, 952.

Insulative jacket 906 can be configured to have a temperature rating between 150 and 200 degrees Centigrade so that the electrically insulative jacket 906 melts or degrades (e.g., chars and crumbles) during soldering of wire 900 to electrodes 40 (e.g., at a temperature of 300 degrees Centigrade) and therefore insulative jacket 906 of wire 900 does not need to be mechanically stripped. In other examples, insulative jacket 906 can have a temperature rating greater than 200 degrees Centigrade to prevent electrically insulating material 902 melting or degrading (e.g., charring and crumbling) during manufacture of medical probe 22 and/or during use. Insulative jacket 906 can be mechanically stripped from wire 900 prior to wires 900 being electrically connected to electrodes 40.

FIG. 10 is a flowchart illustrating a method 1000 of assembling a basket assembly 38, in accordance with an embodiment of the present invention. The method 100 can include cutting 1002 a planar sheet of resilient material to form two connected spirals (e.g., as explained in relation to FIG. 5 ). The planar sheet of resilient material can include shape-memory alloy such as nickel-titanium (also known as Nitinol), cobalt chromium, or any other suitable material. The method 1000 can include forming 1004 a spine having a spherical spiral shape from the two connected spirals. The two spirals can be connected with a linear portion. The method 1006 can further include inserting 1006 the spine into a lumen of one or more electrodes and fitting 1008 an end of the spine into a tubular shaft sized to traverse vasculature. As will be appreciated by one of skill in the art having the benefit of this disclosure, fitting 1008 an end of the spine into a tubular shaft can include attaching the spine 214 to a spine retention hub 90. Furthermore, the spine retention hub 90 and/or the spine 214 and the tubular shaft 84 can be inserted into a flexible insertion tube 30 to form the medical probe 22.

FIG. 11 is a flowchart illustrating another method 1100 of assembling a basket assembly 38, in accordance with an embodiment of the present invention. The method 1100 can include cutting 1102 a cylindrical hollow tube of resilient material to form a spiral (e.g., as explained in relation to FIG. 6 ). The method 1100 can include forming 1104 the spine to have a spherical spiral shape from the spiral, inserting 1106 the spine into a lumen of one or more electrodes, and fitting 1108 an end of the spine into a tubular shaft sized to traverse vasculature. As with method 1000, fitting 1108 an end of the spine into a tubular shaft can include attaching the spine 214 to a spine retention hub 90. Furthermore, the spine retention hub 90 and/or the spine 214 and the tubular shaft 84 can be inserted into a flexible insertion tube 30 to form the medical probe 22.

FIG. 12 is a flowchart illustrating another method 1200 of assembling a basket assembly 38, in accordance with an embodiment of the present invention. The method 1200 can include coiling 1202 an elongated piece of resilient material to form a spine having a spherical spiral shape. The method 1200 can include inserting 1204 the spine into a lumen of one or more electrodes and fitting 1206 an end of the spine into a tubular shaft size to traverse vasculature. As before, fitting 1208 an end of the spine into a tubular shaft can include attaching the spine 214 to a spine retention hub 90. Furthermore, the spine retention hub 90 and/or the spine 214 and the tubular shaft 84 can be inserted into a flexible insertion tube to form the medical probe 22.

Examples are described below which can be used separately or in various permutations with each other and such examples (in various permutations) may be used to define the scope of the invention.

-   -   Example 1) The single spine can include a first end and a second         end. The first end can be positioned proximate the distal end of         the tubular shaft and the second end can be positioned proximate         a distal end of the medical probe in the collapsed form.     -   Example 2) In the expanded form, the single spine can be         configured to spiral (1) outwardly from the first end to a first         location positioned along the single spine between the first end         and the second end and (2) inwardly from the first location to         the second end.     -   Example 3) The single spine can be a single unitary structure         formed from a planar sheet of the resilient material. The single         spine can be formed from the planar sheet of resilient material         by cutting two spirals into the planar sheet of resilient         material. The two spirals can be connected to each other. The         two spirals, for example, can be connected to each other by a         linear portion. The linear portion can be connected to the two         spirals proximate a respective end of each spiral that is         farthest from a central point of each respective spiral. In the         expanded form, the two spirals and the linear portion can be         coiled to form the generally spherical outer periphery of the         single spine.     -   Example 4) The single spine can comprise a continuous elongated         piece of the resilient material that is coiled to form the         generally spherical outer periphery. The single spine can         comprise nitinol, cobalt chromium, or any other suitable         material. The single spine can form an approximately         oblate-spheroid shape.     -   Example 5) The medical probe can further comprise a spine         retention hub disposed proximate the distal end of the tubular         shaft. The spine retention hub can include a cylindrical member         comprising a relief land disposed on the outer surface of the         cylindrical member to allow the single spine to be fitted into         the relief land and retained therein. The retention hub can         further comprise at least one electrode disposed at a distal         portion of the retention hub.     -   Example 6) Each electrode can comprise a relief adjacent the         lumen to allow a wire to extend adjacent to the lumen. The wire         can be electrically insulated from the single spine. The wire         can be electrically connected to the one or more electrodes. At         least a portion of the wire can include an electrically         conductive core material having a first electrical conductivity,         an electrically conductive cover material having a second         electrical conductivity less than the first electrical         conductivity, and an insulative jacket. The electrically         conductive cover material can circumscribe the electrically         conductive core material and the insulative jacket can         circumscribe the electrically conductive cover material.     -   Example 7) At least a portion of the wire can include a         plurality of strands and an insulative jacket circumscribing the         plurality of strands. Each strand of the plurality of strands         can include an electrically conductive core material having a         first electrical conductivity and an electrically conductive         cover material comprising a second electrical conductivity less         than the first electrical conductivity. The electrically         conductive cover material can circumscribe the electrically         conductive core material.     -   Example 8) The medical probe can further include a separate         lumen configured to receive a wire with insulation with the wire         capable of delivering at least 900 volts (V) without dielectric         breakdown of the insulation. The one or more electrodes can be         configured to deliver electrical pulses for irreversible         electroporation. The pulses can have a voltage of at least 900         volts (V).     -   Example 9) The medical probe can further include irrigation         openings disposed proximate the distal end of the tubular shaft.         The irrigation openings can be configured to deliver an         irrigation fluid to an area proximate the one or more         electrodes.     -   Example 10) The medical probe can further include an insulative         sleeve disposed over the single spine and within the lumen of         the respective electrode. The insulative sleeve can include a         first lumen through which a strut extends and a second lumen         through which an electrical wire extends, the first and second         lumens being distinct from each other. A cross-sectional shape         of each electrically insulative sleeve can be a substantially         trapezoidal shape.     -   Example 11) The electrode can include an oblong body type         electrode with the lumen extending through the oblong body. The         electrode can include a bulging type electrode.     -   Example 12) There is provided, in accordance with another         embodiment of the present invention, a method of constructing a         medical probe. The method can include cutting two connected         spirals into a planar sheet of resilient material to form a         single spine. The method can further include forming the single         spine to a predetermined shape having a generally spherical         spiral shape, such that the single spine is configured to         transition from an elongated shape when in a collapsed form to         the predetermined shape when in an expanded form. The method can         include inserting the single spine through at least one lumen of         an electrode and fitting an end of the single spine to a tubular         shaft sized to traverse vasculature such that a first end of the         single spine is positioned proximal a distal end of the tubular         shaft and a second end of the single spine is positioned         proximate a distal end of the medical probe.     -   Example 13) When in the expanded form, the single spine can be         configured to spiral (1) outwardly from the first end to a first         location positioned along the single spine between the first end         and the second end and (2) inwardly from the first location to         the second end.     -   Example 14) Cutting two connected spirals into a planar sheet of         resilient material can include forming a linear portion         connecting the two spirals. The linear portion can be connected         to the two spirals proximate a respective end of each spiral         that is farthest from a central point of each respective spiral.     -   Example 15) The single spine can include nitinol, cobalt         chromium, or any other suitable material. The single spine can         form an approximately oblate-spheroid shape in the predetermined         shape.     -   Example 16) Each electrode can include a relief adjacent the         lumen to allow a wire to extend adjacent to the lumen. The wire         can be electrically insulated from the single spine. The method         can further include electrically connecting the wire to the one         or more electrodes. At least a portion of the wire can include         an electrically conductive core material having a first         electrical conductivity, an electrically conductive cover         material comprising a second electrical conductivity less than         the first electrical conductivity, and an insulative jacket. The         electrically conductive cover material can circumscribe the         electrically conductive core material and the insulative jacket         can circumscribe the electrically conductive cover material. At         least a portion of the wire can include a plurality of strands         and an insulative jacket circumscribing the plurality of         strands. Each strand of the plurality of strands can include an         electrically conductive core material comprising a first         electrical conductivity and an electrically conductive cover         material comprising a second electrical conductivity less than         the first electrical conductivity. The electrically conductive         cover material can circumscribe the electrically conductive core         material.     -   Example 17) The medical probe can include a separate lumen that         is configured to receive a wire with insulation with the wire         capable of delivering at least 900V without dielectric breakdown         of the insulation. The one or more electrodes can be configured         to deliver electrical pulses for irreversible electroporation.         The pulses can be a voltage of at least 900 volts (V).     -   Example 18) The medical probe can further include irrigation         openings disposed proximate the distal end of the tubular shaft.         The irrigation openings can be configured to deliver an         irrigation fluid to an area proximate the one or more         electrodes.     -   Example 19) The method can further include disposing an         insulative sleeve over the single spine and within the lumen of         the respective electrode. The insulative sleeve can include a         first lumen through which a strut extends and a second lumen         through which an electrical wire extends. The first and second         lumens can be distinct from each other. A cross-sectional shape         of each electrically insulative sleeve can be a substantially         trapezoidal shape.     -   Example 20) The electrode can be an oblong body type electrode         with the lumen extending through the oblong body. The electrode         can also be a bulging type electrode.

As will be appreciated by one skilled in the art, the methods 1000, 1100, and 1200 just described can include any of the various features of the disclosed technology described herein and can be varied depending on the particular configuration. Thus, the methods 1000, 1100, and 1200 should not be construed as limited to the particular steps and order of steps explicitly described herein.

The embodiments described above are cited by way of example, and the present invention is not limited by what has been particularly shown and described hereinabove. Rather, the scope of the invention includes both combinations and sub combinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art. 

What is claimed is:
 1. A medical probe, comprising: a tubular shaft having a proximal end and a distal end, the tubular shaft extending along a longitudinal axis; an expandable basket assembly proximate the distal end of the tubular shaft, the expandable basket assembly comprising: a single spine comprising a resilient material extending generally linearly along the longitudinal axis in a collapsed form and forming a spiral member defining a generally spherical outer periphery in an expanded form; and one or more electrodes coupled to the single spine, each electrode comprising a lumen offset with respect to a centroid of the electrode so that the single spine extends through the lumen of each of the one or more electrodes.
 2. The medical probe according to claim 1, the single spine comprising a first end and a second end, the first end being positioned proximate the distal end of the tubular shaft, and the second end being positioned proximate a distal end of the medical probe in the collapsed form.
 3. The medical probe according to claim 2, wherein, in the expanded form, the single spine is configured to spiral (1) outwardly from the first end to a first location positioned along the single spine between the first end and the second end and (2) inwardly from the first location to the second end.
 4. The medical probe according to claim 1, the single spine comprising a single unitary structure being formed from a planar sheet of the resilient material.
 5. The medical probe according to claim 1, the single spine comprising a continuous elongated piece of the resilient material that is coiled to form the generally spherical outer periphery.
 6. The medical probe according to claim 1, wherein the single spine comprises nitinol.
 7. The medical probe according to claim 1, wherein the single spine forms an approximately oblate-spheroid shape.
 8. The medical probe according to claim 1 further comprising a spine retention hub disposed proximate the distal end of the tubular shaft, the spine retention hub including a cylindrical member comprising a relief land disposed on the outer surface of the cylindrical member to allow the single spine to be fitted into the relief land and retained therein, the spine retention hub further comprising at least one electrode disposed at a distal portion of the spine retention hub.
 9. The medical probe according to claim 1, wherein each electrode comprises a relief adjacent the lumen to allow a wire to extend adjacent to the lumen.
 10. The medical probe according to claim 9, wherein the wire is electrically insulated from the single spine and electrically connected to an electrode of the one or more electrodes.
 11. The medical probe according to claim 10, wherein at least a portion of the wire comprises an electrically conductive core material comprising a first electrical conductivity, an electrically conductive cover material comprising a second electrical conductivity less than the first electrical conductivity, the electrically conductive cover material circumscribing the electrically conductive core material, and an insulative jacket circumscribing the electrically conductive cover material.
 12. The medical probe according to claim 10, wherein at least a portion of the wire comprises a plurality of strands and an insulative jacket circumscribing the plurality of strands, and wherein each strand of the plurality of strands respectively comprises an electrically conductive core material comprising a first electrical conductivity and an electrically conductive cover material comprising a second electrical conductivity less than the first electrical conductivity, the electrically conductive cover material circumscribing the electrically conductive core material.
 13. The medical probe according to claim 1, wherein the one or more electrodes are configured to deliver electrical pulses for irreversible electroporation, the pulses having a voltage of at least 900 volts (V).
 14. The medical probe according to claim 1, further comprising irrigation openings disposed proximate the distal end of the tubular shaft, the irrigation openings configured to deliver an irrigation fluid to an area proximate the one or more electrodes.
 15. The medical probe according to claim 1, further comprising an insulative sleeve disposed over the single spine and within the lumen of the respective electrode.
 16. The medical probe according to claim 15, wherein the insulative sleeve comprises a first lumen through which a strut extends and a second lumen through which an electrical wire extends, the first and second lumens being distinct from each other.
 17. The medical probe according to claim 16, wherein a cross-sectional shape of each electrically insulative sleeve comprises a substantially trapezoidal shape.
 18. A method of constructing a medical probe, the method comprising: cutting two connected spirals into a planar sheet of resilient material to form a single spine; forming the single spine to a predetermined shape having a generally spherical spiral shape, such that the single spine is configured to transition from an elongated shape when in a collapsed form to the predetermined shape when in an expanded form; inserting the single spine through at least one lumen of an electrode; and fitting an end of the single spine to a tubular shaft sized to traverse vasculature such that a first end of the single spine is positioned proximal a distal end of the tubular shaft and a second end of the single spine is positioned proximate a distal end of the medical probe.
 19. The method according to claim 18, wherein, when in the expanded form, the single spine is configured to spiral (1) outwardly from the first end to a first location positioned along the single spine between the first end and the second end and (2) inwardly from the first location to the second end.
 20. The method according to claim 18, wherein cutting two connected spirals into a planar sheet of resilient material further comprises forming a linear portion connecting the two spirals, the linear portion being connected to the two spirals proximate a respective end of each spiral that is farthest from a central point of each respective spiral. 